U.S. Pat. Nos. 6,055,484 and 5,937,370 represent a recent, significant development in the field of tool monitoring and assembly qualifying. The programmed microprocessor is configured to identify a portion of the signal representative of the analog signal corresponding to a completed cycle. The configuration also allows for identification of an incomplete cycle and a multiple counting of a completed cycle (double-hit). The qualifiers and disclosures of U.S. Pat. Nos. 6,055,484 and 5,937,370 are herein incorporated by reference.
U.S. Pat. No. 6,810,335 represents the next generation qualifier uses multiple thresholds to perform its operations. This assembly qualifier is a counting apparatus that monitors either the pressure of a pneumatic tool to determine if the tool's clutch has shut the tool off. This version makes use of up to four thresholds and five timers in order to accomplish its qualification of an assembly process. Certain pneumatic pulse tools have an internal mechanical device that regulates (governs) the incoming air supply. Because of this, the pneumatic signature can “fool” the qualifier by creating a signal that would satisfy all of the timers and thresholds even thought the tool was in reverse or running in the air and not tightening a fastener at all.
With these particular pneumatic tools the difference between a “good” run-down and the other anomalies were the pulses. Even though the other qualification methods were used to insured that the pressure was in a window where it was considered to be pulsing, that logic was not sufficient to identify individual pulses. In U.S. Pat. No. 6,810,335 the invention is a pulse counting algorithm that knows how to identify individual pulses. A count of all the positive pulses is kept during a rundown and this pulse count is compared to the desired number of pulses at the end of the run. At the end of the run, if all criteria are met including timers, thresholds, and number of pulses, then the fastening is considered good. The qualifiers and disclosures of U.S. Pat. No. 6,810,335 is herein incorporated by reference.
In the pneumatic, pulse tools of these recent developments, the tool included an internal means of shutting off the tool. A need exits, however, for a system for monitoring and controlling a compressed air driven, pulse tool that does not have an internal mechanism for stopping the tool.